Looking for Parts to Convert 3,500 lb Axle of Big Tex Trailer Axle to Having Brakes

Updated 03/05/2026 | Published 03/01/2026

Products Featured in This Question

etrailer Electric Trailer Brakes - Self-Adjusting - 10" - Left/Right Hand Assemblies - 3.5K

(3094)

$172.99

Trailer Hub and Drum Assembly - 3,500-lb Axles - 10" Diameter - 5 on 4-1/2 - Pre-Greased

(1252)

$91.21

Trailer Hub and Drum Assembly - 3,500-lb Axles - 10" Diameter - 5 on 5 - Pre-Greased

(1252)

$98.46

Question:

I have a 2021 Big Tex 35SA 14foot with a 3500 axel. I am looking to put electric brakes on it but I am not certain of the bolt pattern spacing. 4.5 or 5 Please let me know what type to purchase.

asked by: Todd F

Expert Reply:

Hey Todd, the easiest way to determine your bolt pattern would be to measure the distance from one of the wheel studs centers to one of the studs that is closest to it on center. If the distance is 3 inches its a 5 on 5 inch bolt pattern. If the distance is 2-5/8 inches it would be 5 on 4-1/2 inches which is the much more common bolt pattern.

Either way the brake assemblies part # AKEBRK-35-SA that you referenced would be correct.

Then for hub/drums you'd want the part # AKHD-545-35-K for if they are 5 on 4-1/2 inch or part # AKHD-550-35-K for 5 on 5 inch. Let me know which bolt pattern you have and I can help further if you are still stuck.

expert reply by: Jameson C

Jim M.

3/5/2026

Todd, just for your information, I replaced all four of our trailer brakes and drums with these and was very pleased. The parts fit perfectly and the installation was easy. I recommend them.

Tony J.

3/5/2026

Todd, your trailer uses the 5 on 5" pattern. I recently purchased these trailer brakes for a dual-3500#-axle trailer and they work great. One thing they don't include in the package is good instructions on how to set (or reset) the automatic adjusters. I found these instructions on the eTrailer website (or here you go; back the connected trailer up at around 20-25 mph then hit the brakes. The brakes do the rest. Pretty simple). This is my second set of brakes from eTrailer and I will be going back there again. Safe Trailering.